Is is possible to stop loosing weight while taking the Lipo shots and phentermine?

I have been on these two listed above for almost 2 months and have lost 15 pounds and now have sat on the same weight for two weeks with loosing only a few ounces or gaining a few ounces? Is this normal and what can i do to jumpstart this process again? I exercise 5 days out of 7 and stay within 1200 calorie or less a day. Help